Did the Earth’s lost moon create the Lunar Highlands?

Models have suggested that the collision that formed the Earth's Moon may have …

The Moon's far side, although not lacking for light, remained dark in the sense of hidden or obscured until the space race between the US and USSR took aim at the Moon. The Soviets' Luna 3 probe returned the first images of the far side in 1959, and the results were a bit of a surprise. The near side is covered with large, dark, basaltic flows that are called maria; these are rare on the far side, which is dominated by the rugged lunar highlands. A number of explanations have been offered for this difference, but today's issue of Nature contains what is certainly the most dramatic one yet: it suggests that the highlands are the remains of the Earth's missing moon, plastered across the far side of the one remaining Moon.

A consensus has formed around the theory that the Moon originated from a collision early in the history of the solar system, when a near-Mars sized body smacked into the Earth. The resulting debris coalesced into two bodies. Models of this process nicely account for some of the difference between the Earth and the Moon, including Earth's large, iron rich core. (Robin Canup, who does some of this modeling, has placed videos of the process on her website.)

Frequently, these simulations produce a three body system: the Earth, the Moon, and a smaller companion. In most of these cases, the smaller companion is quickly swallowed up by the Moon while it still primarily molten, erasing all traces of it. But the authors suggest a possible alternative: a small moon could end up in one of the Trojan points, where the gravity of the Earth and Moon cancel each other out, providing a semi-stable home. In this situation, the small companion would be stable for up to 70 million years before a resonance with the gravity of the Sun would pry it from the Trojan point. That would be enough time for the Moon to develop a crust, and for the smaller body (we'll call it Moon II) to solidify entirely.

The authors went on to model what would happen if Moon II, once pried out of the Trojan site, were to end up having its own collision with the Moon. Moon II was estimated to be about a third the size of the existing Moon, with a similar composition, except that it would have an entirely solid crust and core, since its small size would allow it to cool faster. The Moon itself was estimated to still have some molten material (a 50km deep magma ocean), with a 20km deep solid crust floating on top of it. The whole system was modeled as a set of blocks 5km on a side. All that computation was apparently quite expensive, as the authors only test two different collisions, one head-on, the other at a 45 degree angle.

Both of these runs assumed relatively low velocity, just over the two-body escape velocity: 2.4km/s. Because of the difference in masses involved, the authors estimate that the Moon/Moon II impact would carry only 2.5 percent of the kinetic energy that the Moon-forming impact did. It's also below the speed of sound in silicates, one of the primary components of the two bodies involved. And these factors, the authors say, is enough to make it a qualitatively different collision. "Our primary finding," they note, "is that a companion moon, 1/3 the diameter of the Moon, striking at subsonic velocity, does not form a crater." The volume of the impacting body ends up exceeding the volume the impact could possibly excavate. "The impact produces an accretionary pile rather than a crater."

But that doesn't mean that it has no effect on the Moon. For starters, their model suggests that the majority of the magma ocean would get pushed to the opposite side of the Moon, which would explain the preponderance of Maria on that side. In addition, most of the material from Moon II would stay near the point of impact, "pasting on a thickened crust and forming a mountainous region comparable in extent to the far side highlands," they conclude. In short, their model produces something that looks a lot like the actual Moon.

The problem is that, since Moon II probably looked a lot like the Moon in terms of its composition, there's no obvious way of telling which rocks came from which. Crustal rocks originating on the Moon have a wide spread of ages (about 200 million years), which is consistent with multiple origins, but could also be consistent with uneven cooling. And, as noted above, this isn't the first model proposed for the differences between the near and far sides of the Moon (alternatives include things like uneven tidal heating and a large impact near the Moon's South Pole).

Fortunately, a mission that may help resolve this (or at least eliminate the impact model) is already in progress. NASA's GRAIL (Gravity Recovery and Interior Laboratory) will produce the same sort of gravity maps that the GRACE mission is making for the Earth. GRAIL is scheduled to launch next month. If the authors are right, the magma that was pushed off the far side should have left some indications of its shift behind, and these should show up in the gravity analysis.

It's nice to see a theory pop up that is relatively easy to understand and has the possibility of being verified in the near future. Sometimes the more outlandish theories about the universe are so mind-boggling it's hard to tell if its the work of of a genius or a raving lunatic...

I honestly believe that we're overlooking something, and when we finally realise what it is, it'll be like when Newton created his theory of gravity and everyone did a facepalm at how obvious it is and how they hadn't seen the same thing before.

Are we going to rename the Dark Ages as well because some simpletons can't get their heads around the idea that "dark" (and also "light") has more than one meaning? It's called the dark side of the moon for a good reason. We know more about it than we used to of course, but it remains obscured.

I honestly believe that we're overlooking something, and when we finally realise what it is, it'll be like when Newton created his theory of gravity and everyone did a facepalm at how obvious it is and how they hadn't seen the same thing before.

He's not some quack scientist - that was a head astronomer at the US naval observatory. After he retired he presented evidence of alien artifacts on mars and the moon (also of vegetation growing on mars, a conclusion supported by Arthur C Clarke).

Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images...

Oh please, I would love to see a proof of alien activity on Mars, the Moon or whatever, but that site is heavy on "maybe", "possible", "suggestive".... If you look long enough at a random image you will see whatever you want to see. Symmetry and straight lines are not entirely uncommon in nature. None of that is convincing.

Quote and Edit are broken, it seems. My last post was supposed to quote chimly's post.

"Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images..."

Maybe because there aren't nearly as many satellites orbiting Moon as there are orbiting Earth?

(I think truthfully, Dr. Flandern was as disingenuous as NASA... They were probably pretending to fight and disagree with each other. In reality, NASA secretly gave him the data and asked him to lecture about the subject.)

Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images...

Yes, NASA has them, but the CIA keeps them under wraps because there's too much waterboarding going on, on the "dark" side of the moon. =O

...evidence of alien artifacts on mars and the moon (also of vegetation growing on mars, ...

Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images...

Yeah, they do, but they're keeping all the images secret under orders from Lord Vader, wait no, I mean they're online foranyone to download. The Lunar Reconnaissance Orbiter Camera team at ASU has put together a great zoomable web interface to this data; check out the central peak of the Tycho crater or the Apollo 11 landing site. Though for the Apollo one, you might rather look at the press release page instead unless you want to spend a long time manually hunting for a 5-pixel-wide lander in a ~120 megapixel image. Typical image resolution is about 1 meter/pixel, which OK, is not strictly speaking better than Google Earth's best, but remember the finest zooms on Earth were taken from airplanes, which doesn't work on the moon for obvious reasons. :-)

We have extraordinarily good maps of the moon, Mars, Venus, and a decent number of smaller solar system bodies, and we're currently in the midst of mapping Mercury. All this data is out there for you to go download. There are no conspiracies, no hidden alien cities out there being covered up. You seem to think "NASA" is some monolithic entity that can exert dictatorial control over what data "gets out", but that's simply false. Almost all the processing and analysis happens at universities, spread all over the place. The gatekeepers of the data, or closest approximation to such, are grad students in nerdy t-shirts, not men in black suits. Heck, anybody with a big enough radio telescope can just listen to the raw data broadcasts coming in from the spacecraft if they want (this is not a hobbyist item, but it's something that universities can and do operate). It's essentially impossible to keep secrets about something in the sky. Even the things that governments really do want to keep hidden (like spy satellite orbits and capabilities) are widely known and can be checked and verified literally by amateurs in their backyards. So, repeat after me: there are no NASA conspiracies hiding alien cities on the moon, there are no NASA conspiracies hiding alien cities on the moon...

It also raises preposterous questions. Notably where these aliens came from. I can understand the argument being made that on Mars life has persisted from the time when those features of surface water came about. Though its hard to imagine anything greater than microbial life on that harsh planet with no significant protection from solar winds any more.

...evidence of alien artifacts on mars and the moon (also of vegetation growing on mars, ...

Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images...

Yeah, they do, but they're keeping all the images secret under orders from Lord Vader, wait no, I mean they're online foranyone to download. The Lunar Reconnaissance Orbiter Camera team at ASU has put together a great zoomable web interface to this data; check out the central peak of the Tycho crater or the Apollo 11 landing site. Though for the Apollo one, you might rather look at the press release page instead unless you want to spend a long time manually hunting for a 5-pixel-wide lander in a ~120 megapixel image. Typical image resolution is about 1 meter/pixel, which OK, is not strictly speaking better than Google Earth's best, but remember the finest zooms on Earth were taken from airplanes, which doesn't work on the moon for obvious reasons. :-)

We have extraordinarily good maps of the moon, Mars, Venus, and a decent number of smaller solar system bodies, and we're currently in the midst of mapping Mercury. All this data is out there for you to go download. There are no conspiracies, no hidden alien cities out there being covered up. You seem to think "NASA" is some monolithic entity that can exert dictatorial control over what data "gets out", but that's simply false. Almost all the processing and analysis happens at universities, spread all over the place. The gatekeepers of the data, or closest approximation to such, are grad students in nerdy t-shirts, not men in black suits. Heck, anybody with a big enough radio telescope can just listen to the raw data broadcasts coming in from the spacecraft if they want (this is not a hobbyist item, but it's something that universities can and do operate). It's essentially impossible to keep secrets about something in the sky. Even the things that governments really do want to keep hidden (like spy satellite orbits and capabilities) are widely known and can be checked and verified literally by amateurs in their backyards. So, repeat after me: there are no NASA conspiracies hiding alien cities on the moon, there are no NASA conspiracies hiding alien cities on the moon...

No "cities". That's cute.

For those who care, here is a National Press Club conference on UFO disclosure, which includes testimony about structures found on the far side of the moon. Some of these people were deliberately giving falsifiable details (in case denial becomes necessary) but their general stories are meant to be believed.

That's part of the problem. The evidence is "on the far side of the moon"; Why? Also, video/voice tapes by pilots about strange lights or shapes or radar data is not enough.

If there have been space aliens in our solar system for millions of years, the "evidence" of space alien settlements should be visible on earth, the moon and mars. It's not there.The space aliens themselves cannot be produced or they will not make an appearance. Clear evidence that "they" exist is not there.

...evidence of alien artifacts on mars and the moon (also of vegetation growing on mars, ...

Consider this... the moon has near zero atmosphere and it's smaller than the earth. So why don't we have maps of its surface in greater detail than Google Earth? NASA probably does have those images...

Yeah, they do, but they're keeping all the images secret under orders from Lord Vader, wait no, I mean they're online foranyone to download. The Lunar Reconnaissance Orbiter Camera team at ASU has put together a great zoomable web interface to this data; check out the central peak of the Tycho crater or the Apollo 11 landing site. Though for the Apollo one, you might rather look at the press release page instead unless you want to spend a long time manually hunting for a 5-pixel-wide lander in a ~120 megapixel image. Typical image resolution is about 1 meter/pixel, which OK, is not strictly speaking better than Google Earth's best, but remember the finest zooms on Earth were taken from airplanes, which doesn't work on the moon for obvious reasons. :-)

We have extraordinarily good maps of the moon, Mars, Venus, and a decent number of smaller solar system bodies, and we're currently in the midst of mapping Mercury. All this data is out there for you to go download. There are no conspiracies, no hidden alien cities out there being covered up. You seem to think "NASA" is some monolithic entity that can exert dictatorial control over what data "gets out", but that's simply false. Almost all the processing and analysis happens at universities, spread all over the place. The gatekeepers of the data, or closest approximation to such, are grad students in nerdy t-shirts, not men in black suits. Heck, anybody with a big enough radio telescope can just listen to the raw data broadcasts coming in from the spacecraft if they want (this is not a hobbyist item, but it's something that universities can and do operate). It's essentially impossible to keep secrets about something in the sky. Even the things that governments really do want to keep hidden (like spy satellite orbits and capabilities) are widely known and can be checked and verified literally by amateurs in their backyards. So, repeat after me: there are no NASA conspiracies hiding alien cities on the moon, there are no NASA conspiracies hiding alien cities on the moon...

No "cities". That's cute.

For those who care, here is a National Press Club conference on UFO disclosure, which includes testimony about structures found on the far side of the moon. Some of these people were deliberately giving falsifiable details (in case denial becomes necessary) but their general stories are meant to be believed.

Did you read any of what mperrin said? He completely destroyed you yet you're still blabbering on about flying saucers. Try to counter the arguments he passes to you instead of spouting more nonsense.

I'm fascinated by this. Can anyone see when this was projected to have happened? Not within human history, is it?

No, billions of years prior, within a few hundred million years of the initial formation of the solar system from the accretion disc around the sun.

Yeah. Article I read on another site said it happened around the time when the moon was still a fairly molten chunk of caramel floating around the Earth, with a thin crust forming on it. So, if/when this small, secondary moon decided it's game of "I'm not touching you!" was a fail and decided to plow into the bigger moon, it was like smashing into a semi-solid blob of goo. It smashed up, but most of it remained on the side it smashed into, hence the discrepancy in surface types on the moon. The moon reformed into a spherical shape due to gravity, then finally cooled over billions of years. Pretty fascinating theory if you think about it. If it really did happen, it would have been awesome to see.